Paper machinery



Feb. 10, 1953 s. A. STAEGE 2,627,788

- PAPER MACHINERY Filed Feb. 12. 1948 6 Sheets-Sheet l NVENTOR afi q M ATI'ORN EYS Feb. 10, 1953 s. A. STAEGE PAPER MACHINERY Filed Feb.- 12, 1948 '6 Sheets-Sheet 3 ATTORNEYS WZWMQM S. A. STAEGE PAPER MACHINERY Feb. 10, 1953 Filed Feb. 12, 1948 6 Sheets-Sheet 5 INVENTOR ATTORNEYS Feb. 10,1953 s. A. STAEGE 2,627,788

PAPER MACHINERY I Filed Feb. 12, 1948 6' Sheets-Sheet 6 INVENTOR ATTORN EYS Patented Feb. 10, 1953 UNITED STATES PATENT OFFICE PAPER MACHINERY Application February 12, 1948, Serial No. 7,762

20 Claims. 1

This invention relates to paper manufacture and more particularly to controls adapted for use in connection with machines or apparatus for the manufacture of paper.

One of the principal objects of the invention is to provide apparatus for use in paper manufacture to regulate the freeness of the paper making stock which may be connected in the stock supply system of a paper machine at any convenient location and which will continuously measure the freeness of the stock as it passes through the system and automatically regulate the action of a refiner in the system to correct for variations from a desired degree of stock freeness.

Another object is to provide apparatus for efiecting substantially continuous precision control over the consistency of paper making stock as it passes through the stock supply system of a paper machine by measuring the frictional resistance to the flow of stock through a flow passage in the system and by adding water to the stock at an automatically controlled rate to maintain a predetermined frictional resistance having a direct relation to the desired consistency.

An additional object is to provide a regulating apparatus of the above character which may be connected directly in the stock supply system of a paper machine to effect continuous regulation of the consistency and/or freeness of the stock without the loss of any stock from the system and which is thus capable of effecting substantially instantaneous correcting action, in the event of variation in the consistency or freeness of the stock to maintain precision control over the stock for uniform sheet formation.

It is also an object of the invention to provide such regulating apparatus capable of effecting a correcting action which is not continuous but is intermittent within a predetermined time cycle and with which the number and duration of correcting actions in each cycle vary automatically in accordance with the magnitude of the change from the desired condition to give an aggregate correcting action having a direct relation to the total change. I

Still another object is to provide such regulating apparatus which possesses a high degree of sensitivity to even relatively slight variations from the desired stock condition to give precision control and in which in addition the movement of the parts in response to changes in the actuating forces is of such short extent and duration as to minimize wear and to make possible a reliable construction having a long effective life.

A still further object is to provide a stock supply system for a paper machine which includes apparatus for continuously regulating the consistency of the stock as supplied to the refiner and which also includes apparatus for similarly continuously regulating the freeness of the stock as discharged from thhe refiner, and which is thus capable of supplying to the paper machine stock wherein both the fiber content and freeness are continuously maintained with accurately predetermined limits to promote highly uniform sheet formation.

Among other objects of the invention is the provision of a method of regulating the freeness of the paper making stock passing through the stock supply system of a paper machine by continuously measuring the freeness of the stock while flowing continuously through the system and automatically adjusting the action of a refiner in the system to maintain a predetermined measured freeness.

A further-object is to provide a method of maintaining a desired condition such as the consistency or freeness of the paper making stock in the stock supply system of a paper machine by continuously measuring the pressure drop of the stock flowing through a flow passage connected at both ends with the system and by continuously regulating the stock condition in accordance therewith.

Other objects and advantages of the invention will be apparent from the following description, the accompanying drawings and the appended claims.

In the drawings, in which like characters of Fig. 1 is a somewhat schematic view illustrating the operation of the present invention for controlling the consistency of paper stock flowing through a stock supply system;

Fig. 2 isa circuit diagram illustrating the operation of controls utilized in accordance with the present invention for establishing and maintaining a predetermined consistency of paper stock flowing through the system of Fig. 1;

Fig. 3 is a view partly in side elevation and partly broken away and in section on the line 3-3 of Fig. 4 illustrating a gear pump utilized in the system of Fig. 1;

Fig. i is avertical section throughthe gear pump taken on the line 6- of Fig. 3;

Fig. 5 is a section on the line 5-5 of Fig. 3 illustrating the pressure connection to the inlet or suction side of the gear pump;

Fig. 6 is an enlarged view of the control device indicated schematically in Fig. 1, the view being in side elevation with the front cover removed and with parts broken away and in section to illustrate internal construction;

Fig. '7 is a diagrammatic isometric view of the arrangement of cross springs which provides a pivotal mountin in the control device;

Figs. 8 and 9 are sectional views on the lines 8-8 and 9-9, respectively, of Fig. 6;

Fig. 10 is a fragmentary top view illustrating the means for adjusting the device to regulate to a desired consistency;

Fig. 11 is a somewhat diagrammatic fragmentary view showing the cam which operates certain of the electric contacts in the control device;

Fig. 12 is a somewhat schematic view illustrating the operation of the invention for controlling both the consistency and the freeness of the paper stock flowing through a stock supply system;

Fig. 13 is a view in front elevation of a pump and flow passage unit adapted for direct connection in a stock supply system for measuring consistency or freeness;

Fig. 14 is a top plan view of the unit with the motor and motor bracket removed; and

Fig. 15 is a view of the unit partly in side elevation and partly broken away and in vertical section.

Referring to the drawings, which illustrate preferred embodiments of the present invention, Fig. 1 shows a pump i5 arranged to take in stock through conduit l6 from a stock chest or other source of supply and to pump this stock through a conduit IT to the regulating box for a paper machine or refiner or to a machine chest or other container, The pipe I8 is for the purpose of supplying fresh water to the conduit 16 to vary the consistency of the stock supplied by pump l5. The flow of water through pipe I8 is controlled by a metering valve indicated generally at 2B, and this valve is in turn controlled by a reversible electric motor 22 through any suit able driving connection such as the belt or sprocket drive indicated generally at 23.

The stock as supplied initially to conduit 16 is commonly at a relatively higher consistency or fiber density (for example 3.5% or 4% fiber concentration) than that desired at the regulating box or other receiving container to which conduit 11 leads, and valve 20 is accordingly adjusted to admit suflicient water to conduit 16 to reduce the consistency of the stock to the desired value,

for example 3% fiber density. If there are vari- I ations in consistency in the chest or other source of supply connected to conduit l6, varying amounts of water will have to be admitted through valve 20 in order to maintain the desired ultimate consistency, and means are provided in accordance with the present invention for constantly measuring the consistency of the stock flowing through conduit [1 and for controlling valve 29 through motor 22 to admit the proper amount of water required to maintain the desired predetermined consistency of the stock.

Referring to Fig. 1, a pump 25 of any suitable type, shown as a gear pump, has its inlet or suction side connected at 26 to conduit H at a position on the outlet or discharge side of pump 15 in order to draw from conduit I! a sample of stock which has been thoroughly mixed by pump l5 with the water from pipe l8 to obtain a uniform consistency. The outlet of pump 25 is connected with a flow resistance passage formed by a pipe circuit 3!: which is in turn led back and connected at 29 into conduit H at a position substantially directly opposite the connection 26 to the intake side of the pump. The pump 25 is operated by a motor 3! to take in stock continuously through the connection 26 and to pump this stock through the pipe 38 and back into conduit (1.

It will be apparent that the interior surface of the resistance piping 39 offers a certain amount of frictional resistance to the passage of stock 7 therethrough, and this friction will produce a difference between the pressures in the stock adjacent the inlet and outlet of the pump, depending upon the amount of pressure required of pump 25 to force the stock through the pipe circuit 38 into the conduit N. This frictional resistance will be greater for heavier consistency stock than for stock of lighter consistency, which will in turn cause the difference in pressure to vary in accordance with the consistency of the stock. For use in connection with stock of the order of 3% consistency, satisfactory results have been obtained with pipe circuit 30 having a diameter of 3 inches and with this pipe ranging from the order of 5 to 15 or 20 feet in length, which will produce a pressure drop between the two sides of the pump of the order of 2 to 6 pounds. The diameter or" the pipe 30 is preferably increased for stock of higher consistency to assure free discharge from the pump, 4-inch pipe being satisfactory, for example, for handling stock of the order of 5% consistency. It should also be noted that this pipe circuit should be of stainless steel, Monel tubing or other smooth and stainless material which will retain substantially uniform surface friction characteristics in use without being roughened or otherwise afiected by the passage of stock therethrough.

A control device indicated generally at 33 includes differential pressure responsive means provided with pressure connections through conduits 3 and 35 to the inlet and outlet, respectively, of pump 25. This control device 33 includes means for adjusting the diiferential pressure means in order to balance the predetermined pressure drop across the pump which will exist when the stock passing through conduit l7, and being pumped through pipe circuit 38, is at the desired consistency. In addition, the control device 33 includes means actuated by the differential pressure means for controlling the energizing circuits of motor 22. The arrangement is such that if the stock flowing through pipe I! is at the desired consistency, the control device will be in balance, and motor 22 will be idle and will hold valve 26 at the proper setting. However, if the consistency of the stock rises or falls with respect to the desired consistency, the resulting reaction of the differential pressure means will upset the balance of the device and cause closing of an energizing circuit to motor 22 effective to operate the motor in a direction to adjust the setting of valve 20 to admit more or less water as required to correct for the change in the consistency of the stock.

Figs. 3 to 5 illustrate a construction of gear pump which has been found satisfactory for use in the practicing of the present invention. The casing of this pump includes two parts and 4! which are bolted together at 42 and-form the chamber 43 for receiving the two impeller gears it and 45. The casing member 49 also includes a portion 46 defining the intake opening of the pump, and the casing member 4| similarly includes a portion 4'! defining the discharge opening of the pump. Each of these casing members includes downwardly extending leg or bracket portions 48 for supporting the pump, and each also includes a suitable pipe connection flange 50.

It will be noted that the intake opening 46 is shown as of somewhat larger diameter than the discharge opening ll, satisfactory results having been obtained with these openings respectively 4 and 3 inches in diameter, or both 4" diameter.

The impeller gears 44 and are keyed or otherwise secured to shafts 54 and 55, respectively, rotatably mounted in the casing as by means of bearings 56 and provided with suitable sealing members 5! to permit escape of fiuid from within the impeller chamber 43. The teeth of the impeller gears are so proportioned that each has clearance between a pair of adjacent teeth on the opposing gear, as indicated at 6| in Fig. 3. Shafts 54 and 55 are secured together in driving connection by means such as drive gears 64 and in such manner as to maintain the meshing gear teeth in angularly spaced relation,

hard flecks in the stock and tend to cause defects Satisfactory results from this in the sheet. standpoint have been obtained with the clearance 6| between meshing teeth of the order of onesixteenth of an inch.

The driving motor 3| for the pump 25 is shown as bolted to a supporting plate 79 hinged at H to a bracket I2 mounted on the pump casing and shown as secured thereto by means of some of the bolts 42 connecting the casing parts 40 and 4 I. The shaft 54 extends outwardly of the casing, as shown in Fig. 4, and is in driving connection with motor 3| through means such as pulleys 13 and 14 and a belt 15. Bolts I5 are arranged as shown in Fig. 3 to adjust the mounting plate about its pivot H to provide for adjusting the tension of belt 15. Satisfactory results have been obtained with the pump 25 operated at aratesuch that the volume of stock passing therethrough is of the order of 50 gallons per minute, and under ordinary conditions only a relatively small amount of power will be required, for example from .10 to .25 horse power. Accordingly, adequate power should be obtained from a motor 3! of horse power, both for ordinary use and for meeting temporary conditions of extreme thickness in the stock such as may result, for example, after the apparatus has stood idle, and with the motor carried by the pump as shown, the unit is compact and may be supported by the pipe connections without requiring external foundations.

In addition to the clearance 6| between meshing teeth of the impeller gears, these gears 44 and 46 and casing members 46 and 45 are so proportioned as to leave clearance between the teethoithe gears and the adjacent surfaces of the gear chamber 43, as indicated at Tl in Figs. 3 and'4. This clearance further aids in preventing pinching of fibers, and also it facilitates slippage of the stock around the gears in directions opposite to the direction of pumping, which is a useful effect in the practice of the invention. This slippage is closely related to the consistency of the material being pumped, and it increases approximately in inverse proportion with consistency.

6 Thus if, for example, the stock is at a consistency of 2.5%, there will be appreciable slippage of stock around the gears and also between the teeth 50, but this slippage will be substantially less at a consistency of 3% and still less at 3.5% consistency. Actually, therefore, the pump will be discharging a larger volume of stock through the resistance pipe 33 when the consistency is 3% than at a consistency of 2.5%, and still more stock will be discharged when the consistency is 3.5%. This increase in volume further increases the pressure drop across pump 25 with increase in consistency, thus making the control device 33 and the differential pressure means therein more sensitive for the same volume than if the device measured only the differential pressure change due to friction in pipe 33.

It will accordingly be seen that with the pump and control device arranged as described and shown in Fig. '1, it wiil make substantially no difference what volume of stock is being delivered by the pump I5 nor at what pressure. Since the inlet and outlet of pump 25 connect with conduit H at the same pressure level, both are subject to the same pressure conditions existing in conduit l1, and the differential pressure across the pump is accordingly independent of the conditions within the conduit and represents the total pressure drop over the entire length of the branch circulating system including both the inlet pipe 26 and the outlet pipe 30. Furthermore, no stock is lost in the operation of the control apparatus, since the pump 25 and pipe 39 merely operate as an auxiliary circulation system and return to the main conduit all of the stock withdrawn therefrom. In addition, it will be apparent that this control apparatus is not limited to use with a pipeline wherein stock is running under pressure, but it can also be connected to other types of containers such as an open vat or chest or stock box of any kind. For such uses it is desirable that the intake of the pump and the discharge end of pipe 30 be connected at the same level to assure that both sides of the pump will be subject to the same static pressure conditions.

Means such as a membrane diaphragm may be provided in the pressure connections between tubes or conduits 34 and 35 and the pump 25 to prevent fiber or other material suspended in the fluid in conduit H from entering the differential pressure means of the control device 33. Figs. 3 and 5 illustrate a pressure connection including such a diaphragm between the conduit 34 and the inlet side of pump 25. The casing part 40 is formed on one side with a pipe connection flange B! to which is bolted or screwed a plate 82 having a central recess therein. The diaphragm 80 is clamped between the plate 82 and a clamp ring 8 3, thus dividing the chamber formed by the outer surface of flange 8| and the recess in plate 82 into inner and outer chamber sections 84 and 85, respectively. A hole 85 is drilled through the casing part 46 to provide open communication between the inner chamber section 84 and the interior of the intake of the pump. A hole 88 in plate 82 is provided with a nipple 83 or like member for connection to the conduit or tube 34. Plate 82 is also provided with a pipe fitting 90 having a removable closure plug 9| for filling the outer chamber section 85 and the conduit 34 with water or other clear liquid.

The casing part 4| at the discharge side of the pump is provided with a similar connection unit to the tube or conduit 35, and this connection unit is indicated generally at 95 and includes a pipe fitting 96 and substantially the same other component parts as the pressure connection between the tube or conduit 34 and the suction side of the pump. With this arrangement, changes in pressure at the inlet and outlet of the pump are readily transmitted through diaphragm 80 to the outer chamber section 85 and thence through conduit 34 to the pressure responsive means in the control device 33, and similarly through the corresponding diaphragm at the discharge side of the pump to control device 33 through the conduit 35.

The control device 33 is illustrated in detail in Figs. 6 to 11, and it includes a generally box-like casing or frame I provided with a back closure plate IM and front closure plate I02, the latter being shown as transparent to facilitate observation of the operating parts of the device. The case i00 may be mounted in any convenient location adjacent the pump 25 by means such as a pipe or bracket I03. The differential pressure means are shown as comprising a pair of pressure responsive bellows I04 and 105. The bel lows I04 is a metal bellows having a large number of convolutions and mounted in a cup I06 bolted or otherwise secured to the top of casing I00 and provided at its upper end with means such as a nipple I01 for connection to the tube or conduit 34. This bellows I04 is arranged for ment in the opposite direction, its upper end be- 1 ing soldered or otherwise sealed to the top of cup IIO. A rod I II is secured to the bottom of bellows I and passes through a hole H2 in the upper end of cup H0, and the lower end of cup H0 is shown as provided with a nipple II 3 for connection to the tube or conduit 35. Means such as a petcock II4 are provided at the top of cup IIO to permit escape of air while the cup is being filled with liquid, thus providing for complete absence from the bellows system of air pockets tending to cushion the transmission to the bellows of any changes in liquid pressure at the discharge side of pump 25, and in use the device should be positioned at such level with respect to the pump 25 that the line pressure will maintain both bellows completely filled and properly distended.

The rods I08 and III are pivotally secured, as by a pin H5 and clevises H6 and II! to a beam I pivotally mounted within casing I00 by means of cross springs for limited movement in response to changes in the relative pressures effective on bellows I04 and I05. Referring to Figs. 6 to 9, beam I20 is welded or otherwise secured at one end to a block I2I which is secured by bolts I22 and a plate or strap I23 to one flanged end I24 of a Zshaped spring I25. The other end I26 of spring I is similarly secured by bolts I21 and a plate or strap I28 to a block I00 secured by bolts I3I to the end wall of casing I00. Blocks I2I and I30 are further connected at each end by a pair of flat springs I32, which are secured thereto by plates or washers I33 and bolts I34.

These three cross springs I25 and I32 thus form a pivotal mounting for beam 20 allowin the beam to move with relatively low friction and relatively minute spring losses to provide high sensitivity in use. Stops I35 are provided at the opposite end of the casing from the pivotal mounting of the beam to limit this movement of the free end of the beam, satisfactory results having been obtained with these stops arranged to permit a total range of movement of approximately .25 inch for the free end of the beam, thus minimizing the total deflection of the cross springs I25 and IE2 and correspondingly reducing the stresses thereon in use.

It will accordingly be seen that the bellows I04 and I05 combine with beam I20 to form a difierential pressure unit responsive to the difference in relative pressures existing at the intake and discharge sides of pump 25. The pressures efiective on the two bellows I04 and I05 will vary in accordance with the consistency of the stock running through the pump, and variations in consistency will produce corresponding variations in these effective pressures, which will in turn be translated into movement of the bellows in opposite directions and corresponding pivotal movement of beam I20 to provide continuous measurements of consistency. Accordingly, the device is provided with means for regulating beam I20 to establish a neutral position when the consistency of the stock is such that the proper predetermined differential pressure or difference in relative pressures is being maintained, and the regulating means are adjustable to provide for setting the device to maintain different consistencies.

Referring particularly to Figs. 6 and 10, a threaded rod or adjusting screw I is rotatably supported at one end in an ear or lug I4! mounted on the free end of beam 220, this end of screw its being of reduce-:1 diameter and being held against axial movement relative to lug MI by a collar I42 as shown in Fig. 6. The other end of screw I40 is supported in a yoke or lug I43 mounted adjacent the pivoted end of beam I20, and it extends through a hole I44 in the casing wall and is provided with a knurled adjusting knob 8&5, this hole I44 being of sufiiciently larger diameter than screw I40 to allow for lateral movement of the screw with beam I20. A short sleeve I45 is welded to the outer side of the casing wall surrounding hole I44 to guard against entry of water into the casing when the paper machine or other apparatus is being washed up after use.

A weight IE0 is mounted for axial movement with respect to beam I20 in response to rotation of screw I40. Referring to Figs. 6, 9 and 10, weight I is slotted at I5I to straddle beam I20, and two bolts or pins I52 extend through this slot and ride on the beam to support the weight I50 therefrom. The adjusting screw I40 also traverses slot I5I, and it carries a nut I55 which fits within slot I56 in weight I50 arranged at right angles to slot I5! and of such dimensions as to hold nut I55 against both rotation and axial movement with respect to weight I50. Accordingly, when screw M0 is rotated, nut I55 will be caused to move axially thereof and of beam I20, thus causing corresponding movement of weight E50 relative to beam I20 to vary the differential pressure which the pair of bellows will balance.

The device can thus be readily adjusted to the control of a desired differential pressure in accordance with a desired consistency of stock or other fluid by appropriate adjustment of screw I40 to a position of weight 550 at which beam I20 is balanced in neutral position between the stops I35 when the desired consistency and differential pressure are being maintained. To facilitate this adjustment, a pointer I5? or other indicator may be mounted on weight I58, as by means of one of the pins I52 as shown in Figs. 6 and 9, and arsuitable scale may be etched or otherwise provided on the transparent front plate I02 of the casing, as indicated at I50, in cooperation with the pointer I5? for readily visible adjustment. The beam I20 thus always occupies substantially the same position when the system is in balance regardless of the difierential pressure for which the device is adjusted, thus contributing to minimizing stress on the bellows and on the cross springs I25 and I32 in use. It should also be noted that the movements of beam I20 under ordinary conditions of use are within a narrow range, since the movements of the bellows I and I are of the order of only a few thousandths of an inch. The movements of the diaphragm 80 and the similar diaphragm in the connection unit 95 are correspondingly within a narrow range, and hence deformation of the diaphragms will have no appreciable efiect on the accuracy of the device.

As pointed out, the control device 33 includes means actuated by the differential pressure responsive means for controlling the energizing circuits of the motor 22 which operates the metering valve 20. These control means are effective to cause energizing of motor 22 only when beam I20 moves out of its balanced or neutral position as a result of change in the differential pressure effective on bellows I08 and I 05. addition, these control means actuate motor 22 in accordance with a periodic cycle and are efiective to vary the frequency or number and the duration of operative intervals of the motor in each such cycle of the control means in accordance with the magnitude of the change in consistency to be corrected for.

Referring to Figs. 6 and 9, a bar N35 is bolted or otherwise secured at I 08 to the free end of beam I20 and extends downwardly therefrom. This bar carries two vertically spaced circuit controlling members; shown as spring contacts I and HI, which are secured to a pair of yoke arms In electrically insulated from each other and from bar I65 by blocks I13 and I'M of suitable insulating material bolted to bar 65, the yokes I12 being riveted or otherwise secured to block I13 as indicated in Figs. 6 and 9. Thumb screws I75 are mounted in yokes I12 and engage contacts I70 and IlI as shown in Fig. 6 to regulate the relative spacing between these contacts. Bar I65 is also shown as provided with an outwardly projecting lug I78 forming a mounting for one end of a small biasing spring II'I (Fig. 6) having its other end secured to the lower of stops I35 and serving to reduce extreme sensitivity of beam I29 in cases where there is rapid variation in the differential pressure effective on bellows I04 and I05.

Two additional circuit controlling members, shown as spring contacts I80 and iill, are mounted in the casing I00 in cooperating relation with contacts lit and HI, respectively, and are movable with respect thereto. Referring to Figs. 6 and 9, the contacts I89 and IBI are secured to yoke arms l82 carried by a block or bar I83 of electrically insulating material which is secured to the base of easing I90 as by means of angle bracket I84. Thumb screws I85 are mounted in yoke arms I82 as shown in Fig. 6

10 and engage the contacts I and I8I to regulate the relative spacing and tension of these contacts.

The two pairs of contacts I'I0I80 and Iii-I8I are connected in circuits controlling the energizing of motor 22, the contacts in each such pair cooperating with each other to open and close one of a pair of selectively operable control circuits to motor 22 as described in detail hereinafter in connection with the circuit diagram in Fig. 2. The relative spacing of these contacts is so controlled that when the system is in balance, with the differential pressure on bellows I04 and I05 balancing weight I50 to support beam I20 in its neutral position, neither pair of contacts will be in circuit closing relation, but when the relative pressures effective on the bellows change, the free end of beam I20 will rise or fall correspondingly, thus carrying one of contacts I10 and I'll into circuit closing relation with its cooperating contact I80 or I8I.

Means are also provided for causing continuous movement of contacts I80 and NH towards and away from their respective cooperating contacts I10 and Ill, and for continuously varying the extent of this movement of contacts I80 and I8I to establish periodic operating cycles for the control means comprising a plurality of low points alternating with a plurality of high points of relatively different heights. As a result, when the device is out of balance the number of intervals in each such cycle during which the active pair of contacts is in circuit closing relation is caused to vary in substantially direct relation to the magnitude of the change in differential pressure to be corrected for, and hence the extent to which the beam I20 and contacts I70 and I'll have been moved, and the duration of each such operative interval is similarly caused to vary.

Referring to Figs. 6, 9 and 11, a polygonal cam I 90 is mounted between contacts I80 and I8I for rotation on a shaft I9I continuously driven at a desired speed by a motor I92, such as a small electric clock motor, mounted on the base of casing I00 by a bracket I93. The cam I90 is shown as octagonal, and each corner or lobe I95 is arranged at a progressively different radial distance from the axis of shaft I9I. Thus referring to Fig. 11, the corner or lobe I95a is the highest of the eight high points of the cam, as shown by the dotted circle I96 which is centered on shaft I9I and has a radius equal to the radial distance from the lobe I95a to the axis of shaft I9I. Each of the other high points or lobes I951) to I95h, inclusive, is arranged at a progressively lesser distance from the axis of shaft I9I and hence lies within circle I96. Satisfactory results have been obtained with each of these lobes or high points closer by 0.005 inch to the axis of shaft I9I than the adjacent higher high point, and the corner or lobe I95h thus represents the lowest of the plurality of high points of the cam and is 0.035 inch lower than the high point I95a, these dimensions being considerably exaggerated in Fig. 11 for purposes of illustration.

In use, the tension of contacts I80 and I8I is adjusted by thumb screws I so that both contacts will be in engagement with cam I at all times during a complete revolution of the cam. Each of these contacts will thus be caused to oscillate in periodic cycles corresponding to a complete revolution of the cam and each comprising alternate high points and low points of differentheights, the low points being the points on each of the flat sides I9! of the cam which are closest to the axis of shaft NH. The length of each of these periodic cycles is determined by the speed of motor I92, satisfactory results having been obtained with this speed relatively low, for example 4 R. P. M. providing cycles of 15 seconds duration, and with each cam lobe formed with a sharp peak as shown, the electric contact between a pair of contacts I'M-I80 or I'll-IBI can be controlled to as short an interval as onequarter second. It is also to be noted that under some conditions of relative dimensions, one or more of the low points of the cam, for examplc the low point between the highest two high points I951; and I951 may be relatively higher than one or more of the lowest of the high points. In such case, however, the corresponding low point between such lower high points will be relatively still lower, thus maintaining the desired alteration between low points and high points of different heights in each cycle.

Fig. 2 illustrates control circuits for operating the valve motor 22 in response to rising or falling movement of beam I20 occasioned by changes in the relative pressures efiective on bellows I04 and I05. Motor 22 is shown as energized from a three-phase source of power I99, and the motor is controlled through the provision of magnetic reversing switches 250 and 29I in a switch unit identified generally as 202. Suitable upper and lower limit switches 205 and 206 are connected in the circuit of each reversing switch so that the control circuits of the valve motor22 will be de-energized when the valve 20 reaches either of its limiting positions, whereby avoiding the possibility of damage to the motor or valve.

A control circuit for actuating the reversing switches 20! and 202 is energized from the low voltage secondary of a transformer 209, and push button switches 2 I and 2H provide for manual actuation of the respective reversing switches for rapid setting of the valve 20 when the operator wishes to establish a substantial change in the consistency of the stock or other fluid being controlled. A manually operable reversing switch 2 I2 provides for shifting the device between automatic operation through the contacts II0-I80 or I'II-I8I and manual operation through switch 2I0 or 2I I, these switches being readily grouped in a unit identified generally as 2I5. It will be understood that for manual operation it is necessary merely for the operator to shift switch 2I2 to the proper position and then to close either of the switches 2I0 or 2I I, and that the motor 22 will then continue to. operate valve 20 in the selected direction so long as the switch is closed, or until the corresponding limit switch 205 or 206 opens.

In operation with the circuit arrangement shown in Fig. 2, the weight I50 is adjusted to balance the predetermined difierential pressure effective on bellows I04 and I05 when the stock flowing through conduit I1 is at the desired consistency, and the contacts I and III are initially adjusted by means of thumb screws I to a relative spacing such that when the beam I is in its neutral or balanced position, each of these contacts will be out of contact with its associated contact I80 or I8I throughout the complete revolution of cam I90. This adjustment determines the extent of fluctuation in the consistency of the stock which may take place before the control device is efiective to actuate valve motor 22, and it is accordingly controlled in accordance with the desired accuracy with which the con- 12 sistency of the stock, is to be maintained. At the least, the adjustment should be such as to leave sufiicient margin between each of contacts I10 and I II and its associated contact I80 or I8I so that when the beam I20 is in its neutral or balanced position, the contacts in each pair will be out of circuit closing relation throughout the complete cycle of cam I95. Accordingly, when the proper consistency and differential pressure are being maintained, the circuits through both pairs of contacts I'I0-IBO and I'II-I8I will remain open, thus rendering motor 22 inactive and holding valve 20 in position to admit water into conduit I6 at the proper rate.

As soon as a change occurs in the consistency of the stock flowing through conduit I1 and being withdrawn therefrom by pump 25, for example if the consistency increases, this will be translated into a greater increase in the pressure at the discharge side of pump 25 than at the suction side of the pump, thus similarly increasing the pressure on bellows I05 and the difierential pressure on the two bellows. This will in turn cause the free end of beam I20 to rise and to carry contact "I in the direction of its oscillating cooperating contact I8I, the extent of this movement being substantially proportional to the magnitude of the change in the differential pressure. When this movement has been sufl'lcient to carry contact III within the oscillating range of contact I8I as determined by the initial adjustment of contact I'II through its thumb screw I15, 1. e.. within the maximum range of movement of contact IBI determined by the highest and lowest points of the cam, there will be electric contact between contacts Ill and I 8i, thus closing the circuit to the magnetic reversing switch 20I and causing operation of motor 22 in a direction to cause valve 20 to open and thus to increase the rate at which water is added to the stock in conduit H5.

The number of intervals of contact between contacts HI and I8I in each revolution of cam I90, and the duration of each such interval, are determined by the magnitude of change in consistency and hence the extent to which contact III has been raised, as will now be explained. If cam I rotates in clockwise direction as viewed in Fig. 11, during each complete revolution of the cam, contact I8I oscillates in a cycle comprising eight high points, each high point being .005 inch lower than the preceding high point in the cycle. As soon as contact III has moved within range of at least the highest of these high points, corresponding to the corner or lobe Ia of the cam, the two contacts will touch and close the operating circuit to motor 22 at least during the instant when contact I8I is passing over the camlobe I 95a. If the change in. consistency has been fairly substantial, contact I'II may also move within range of some of the other high points on the cam, and each time the contacts thus close one of its energizing circuits, the motor 22 will operate to cause a correcting action in the system. Then as soon as the stock to which additional water is added passes through pump I5 and reaches pump 25, it will produce a change in the difierential pressure effective on bellows I04 and I05 resulting in return movement of beam I20 and contact "I towards neutral position.

The correcting action of motor 22 will continue only during the interval when the circuit through contacts Ill and I8I is closed. For relatively slight changes in consistency, the correction produced by a single operative interval of motor 22:

may be adequate to restore the proper consistency and differential pressure and thus to cause return of contact I 'H to its neutral position and to limit its engagement with contact IBI to a single interval, or possibly to a single interval in one or two cycles of the cam. However, for relatively larger changes in consistency, movement of contact I'll will carry it within range of a plurality of the high points of contact thus increasing the number of operative intervals of motor 22 during each revolution of the cam.

It should also be noted that the contacts may touch for an instant before and after a high point or lobe of the cam passes the contact ill, and for greater errors the contacts may remain in engagement during the interval corresponding with the fiat side 59? between one or more adjacent pairs of high points of the cam. Thus the intervals of the correcting action in normal operation may vary upwards from as short a time as a fraction of a second depending upon the magnitude of the error or change from the desired consistency being maintained.

The initial engagement between the two contacts at the start of each cam cycle will take place at the high point represented by the cam lobe l95a. This interval of engagement will usually be of longer duration than the others in the cycle, since the parts of the cam sides lSl adjacent corner or lobe 195a are relatively higher than the corresponding portions of the cam sides adjacent the other lob-es. Thus at the start of each cycle when the system is out of balance, there may be an appreciable interval of circuit closing engagement between the contacts, followed by one or more additional intervals of engagement, each of lesser duration and corresponding to the higher of cam lobes i95b to l95h, until the oscillating contact l8l no longer engages the contact ill at the lower high points of the cycle. During this relatively longer inoperative interval, the device will have more opportunity to return to its balanced position as the correcting actions of motor 22 and valve 29 take effect in the stock, so that in the next cycle or revolution of the cam, both the number and the duration of operative intervals will be decreased, and this diminishing action will continue until balance is restored to the system and the desired consistency of the stock is again established.

The cycle of cam 59E! should accordingly be of such duration that under conditions of relatively small variation, adequate time will be provided between corresponding high points in successive cycles to allow the correcting action of the first such high point to take effect in the system before the corresponding high point in the next cycle is reached and thus to prevent over-correction. The proper cycle length for a particular installation will thus depend upon the operating conditions involved, including particularly the interval required for a correcting action to cause a change in the pressures effective on the control device, and satisfactory results have been obtained with a system of the type illustrated in Fig. 1 with the cam l Bil rotating at 4 R. P. M. as stated.

It will accordingly be seen that the correcting action of this device is not continuous but will be intermittent during each revolution of the cam except under conditions of such large change in consistency as to cause movement of beam lZil to a position in which one of contacts I!!! or Ill is in circuit closing relation with its cooperating contact 88 or 18! throughout one or more complete revolutions of the cam. Also, since the effect of the first circuit closing engagement between a pair of contacts in each cycle will be felt in the system during the interval represented by the flat side it! of the cam between the lobes i555; and lfifib and will cause the beam I20 to start to move in the opposite direction, the interval of operative engagement between the two contacts at the next high point in the cycle will be shorter than would be the case if the beam remained stationary, and so forth until balance is again restored.

Thus both the number and duration of operative intervals of the regulating means in each cyle will vary in accordance with the magnitude of the change in consistency to be corrected for, to give an aggregate operative interval for motor 22 and an aggregate correcting action which will be in substantially direct relation to the magnitude of the change or variation from the desired consistency as predetermined by the initial adjustment of the device through weight I50. Furthermore, this modulating precision control will substantially eliminate tendencies toward overcorrecticn and will eiiectively maintain the desired stock consistency with minimum fluctuation.

The control apparatus described in connection with Figs. 1 to 11 is also adapted for use to pro- 1 vide precision control over the freeness of the paper making stock in the stock supply system of a. paper machine, the property of freeness being a measure of the slipperiness of the stock and being commonly defined in terms of the rate at which he water in the stock will drain from the fiber and other solid material. After the raw stool; has passed through one or more refiners, it will be found to have considerably increased slipperiness even before any filler has been added, and it is at this stage of preparation that the stock is commonly characterized in terms of freeness. Although the refined stock still contains the same percentage of fiber, its frictional properties are considerably lower, so that the pressure drop for a given volume of flow through a pipe of given length will be substantially less than before the stock is passed through the refiner. However, this pressure drop can be measured in the same manner as described in connection with the regulation of consistency, and the refining action of the refiner can be controlled to maintain a predetermined pressure drop in accordance with the desired freeness.

Fig. 12 illustrates in schematic outline a stock supply system in which the consistency of the raw stock supplied to a refiner is controlled as described in connection with Figs. 1 to 11, and the freeness is similarly controlled by measuring the friction of the refined stock in a pipe and by adjusting the refiner to maintain a predetermined freeness in accordance with the measured frictional properties of the resulting refined stock. In Fig. 12, the pump 220 is arranged to take in raw stock through a conduit 22! from a raw stock chest 222 and to pump this stock through a conduit 223 to a refiner 225 such as a Jordan including a relatively rotating tapered plug and shell driven by a motor 226. The plug and shell of the refiner 225 are arranged for relative axial adjustment by means of a screw 22! to vary the spacing of their refining surfaces and thus to vary the refining action on the stock. The screw 22'! is in turn controlled by a reversible electric motor 230. A conduit 23! is arranged to conduct the refined stock from refiner 225 to a collecting box 232 from which a conduit 233 controlled by a valve 234 leads to the paper machine.

A pipe 235 in Fig. 12 corresponds to the pipe !8 in Fig. 1 and supplies fresh water to the conduit 22! to vary the consistency of the raw stock supplied by pump 222. The flow of water through pipe 235 is controlled by a metering valve 235 which is in turn controlled by a reversible electric motor 231 through the belt or sprocket drive 238. The motor 23'! is actuated by a control device 243 as indicated by the dotted line 24! The control device 240 corresponds to the control device 33 of Fig. 1 and is arranged to measure the pressure drop across pump 242 having its inlet connected to conduit 223 by a pipe 243 and its outlet similarly connected by a pipe 244 back to the conduit 223 at a position opposite inlet pipe 243. The construction and operation of these parts are the same as already described in connection with Figs. 1 to 11, and the control device 240 actuates motor 23? to adjust the valve 235 to a position admitting water to conduit 22! at a sufficient rate to maintain a predetermined pressure drop across pump 242 in accordance with the stock consistency desired at the collecting box 232.

A pump 255 corresponding in construction and operation to the pump 232 has its inlet connected by pipe 25! to the conduit 23! on the discharge side of refiner 225, and the outlet of pump 250 is similarly connected by a pipe 252 back to the conduit 23! at a position opposite the inlet pipe 25! to effect continuous withdrawal of a specimen of refined stock from conduit 231 and then to return this specimen back into the system. A control device 255 similar in construction and operation to the control devices 33 and 240 is connected as indicated at 256 and 251 to the inlet and discharge sides of pump 250 to measure the pressure drop across the pump. The control device 255 is in turn provided with an operative connection 260 to the motor 230, for example by means of control circuits substantially the same as those connecting the control device 33 and the motor 22 in Fig. 2.

With this construction and arrangement as shown in Fig. 12, the control device 250 continuously measures the pressure drop across pump 252 which varies in accordance with the freeness of the refined stock. The device is initially calibrated in terms of any suitable freeness scale, as by providing suitable graduations 58 on the transparent front panel of the device as described in connection with Figs. 6 to 9.

In operation, the device is adjusted to balance a predetermined pressure drop across pump 242 corresponding to the desired degree of freeness of the stock. So long as this ireeness is maintained in the stock, the device will remain in balance and the refining action of refiner 225 will continue unchanged. In the event of variation in freeness resultin in a different pressure drop across the pump, the control device 255 will function in the same manner as device 33 to actuate motor 230 and thus to adjust the refiner plug and shell sufiiciently to correct for the variation in ireeness and to restore the predetermined pressure drop. The operation of device 255 in producing such correcting actions will be substantially the same as already described in connection with Figs. 1 to 11 and will result in precision control over the freeness of the stock supplied to collecting b x 232 with minimum fluctuation. It should also be noted that the device 255 is shown as connected in the system at a location ahead of the position where filler is added to the stock. This is a desirable arrangement as giving a more accurate indication of the extent to which the freeness of the stock is due to the action of the refiner, in view of the fact that the addition of filler usually produces a considerable apparent change in freeness.

Figs. 13 to 15 show a combined pump and resistance passage unit which is adapted for coupling as a unit directly into a stock supply system such as those shown in Figs. 1 and 12. It includes a relatively short pipe section 300 of a size standard for use in stock conduits such as the conduits I6 and I! in Fig. 1 and the other conduits in Fig. 12, a 10 inch pipe being an example of a suitable size. This pipe section 300 is provided with pipe flanges 30! and 302 for bolting to the conduit pipes of a stock supply system, which are indicated fragmentarily at 303 and 354 as provided with similar flanges. A. gear pump 305 is connected on its intake or suction side with the pipe section 300 by means of a nipple 306 welded to the pipe 300. The discharge side of the pump is similarly connected to the pipe 300 by means of flow resistance tubing 3H) of suitable length, for example 12 to 15 feet, which is wound helically about the pipe 300 and has one end 3 connected to the pump and the other end welded at 312 to pipe 300 at a position opposite the nipple 306. The nipple 30B and tubing 3!!) thus combine to support the pump directly on pipe section 300.

The pump 305 is similar in its internal construction to the pump 25 as already described. and it includes impeller gears 3!5 and driving gears 3H5 and 3". The gear 3H5 is driven by means of a pulley 320 positioned on the outside oi the pump housing and in driving connection through belt 32! and pulley 322 with a motor 325 of suitable capacity such as a H. P. motor. The motor 325 is supported on a bracket 326 which is in turn secured to the pipe flange 302 on pipe section 300, thus maintaining the motor in desired fixed relation with respect to the pump 305.

The housing or" pump 305 includes means pro viding pressure connections to the control device of the invention. As shown in Fig. 15, a diaphragm 330 similar to the diaphragm is mounted at the intake side of the pump by means of a flanged mounting disk 33! bolted to the pump housing. The diaphragm 330 is clamped to the disk 33! by means of a bolted clamp ring 332. A pipe or hose 333 leads from the disk 33! for connection to one of the bellows in a control device of the construction described in connection with Figs. 6 to 11, and a fitting 335 is also secured to disk 33! for filling the system with water as described in connection with the parts 30 and 9! in Fig. 5. This construction of diaphragm unit is well adapted for use in connection with high consistency stock since it is full of pockets in which suspended materials might collect. A similar diaphragm unit 340 is similarly mounted at the discharge side of the pump, and it includes a pipe or hose 34! for connection to the other bellows in the control device and also a fitting 342 for filling the system with water.

It will be seen that this unit can be readily cut in to an existing stock pipe line at any convenient location by means of the pipe flanges 30! and 302, and it will occupy comparatively little space and will require no additional supporting structure. The control device can similarly be located wherever convenient for purposes of adjustment, and the bellows therein connected to the diaphragm units by suitable lengths of pipe or hose 333 and 36!. This unit is thus well adapted for use in connection with the control of either consistency or freeness as described above.

The present invention accordingly provides simple and rugged control apparatus for efiecting precision control over the physical properties of a fluid within a narrow range. With the apparatus constructed and operated as illustrated and described, the overall sensitivity has been found to be such that the device will respond promptly and accurately to changes in differential pressure as slight as approximately 0.19 inch head of water and will detect and correct for changes in consistency as small as of the order of 0.05% consistency or less. The invention is accordingly particularly well suited for use in connection with paper manufacture to give the ac-- curate control over the consistency and freeness of the stock required for maximum uniformity of sheet production. The invention also provides for installation of the control device at any desired position for convenient handling and adjustment, and for connecting the device with the stock or other fluid at any convenient location in the handling or supply system for the fluid such that the accuracy of the device will not be affected by changes in pressure or other conditions eilective on the system or supply of fluid as a whole.

Reference is made to the application of the same inventor, Serial No. 7,761 filed of even date herewith and assigned to the same assignee as this application.

While the methods herein described, and the forms of apparatus for carrying these methods into effect, constitute preferred embodiments of the invention, it is to be understood that the invention is not limited to these precise methods and forms of apparatus, and that changes may be made in either without departing from the scope of the invention which is defined in the appended claims.

What is claimed is:

1. Apparatus of the character described for effecting continuous regulation of a predetermined physical property of the paper making stock in the stock supply system of a paper making machine, comprising a conduit in said system through which said stock flows, a pump, means connecting the inlet of said pump to said conduit to effect continuous Withdrawal of stock from said conduit, a flow passage providing a return connection from the outlet of said pump to said conduit for continuously returning said withdrawn stock to said conduit, said passage being connected with said conduit at substantially the same pressure level as said inlet and having such flow resistance as to provide a readily measureable pressure drop of the stock flowing therethrough in relation to said predetermined physical property of said stock, diiicrential pressure means including a movable part having pressure connections with the inlet and. outlet of said pump to measure the total drop from line pressure of the stock passing through pump, regulating means positioned in said stock supply system ahead of said pump inlet for effecting change in said physical property of said stock, a counter-balance for establishing a neutral position for said movable part when said pressure drop is within a predetermined range, and means including an operative connection between said 18 differential pressure means and said regulating means for actuating said regulating means in response to movement of said movable part from said neutral position.

2. Apparatus of the character described for maintaining a predetermined consistency range for the paper making stock in the stock supply system of a paper machine comprising a pump, means connecting the inlet of said pump to said stock supply system to effect continuous with:- drawal of a specimen of said stock, a flow passage providing a return connection from'the outlet of said pump to said system, said passage having such flow resistance as to provide a readily measurable pressure drop of the stock flowing therethrough in relation to the consist ency of said stock, means including a plurality of pressure connections with said passage for: continuously measuring said pressure drop, intermittently operable meansfor regulating the consistency of said stock' in said system, a drive controlled by said measuring means for actuating said regulating means, a periodically operative control for varying the frequency and duration of the operative intervals of said drive in direct relation to the magnitude of change in the consistency of said stock.

3. Apparatus of the character described for maintaining a predetermined consistency range for the paper making stock in the stock supply system of a paper machine; aidsystem' including a conduit through which said stock flows; said apparatus comprising a pump, means connecting the inlet of said pump to said conduit to efiect continuous withdrawal of a specimen of said stock, a flow passage providing a return connection from the outlet of said pump to said conduit and connecting with said conduit atsubstantially the same pressure level as said inlet connecting means, said passage having such flow resistance as to provide a readily measurable pressure drop of the stock flowing therethrough in relation to the consistency of said stock, differential pressure means including a plurality of pressure connections with said passage responsive to said pressure drop, means for regulating the consistency of said stock, an intermittently operable drive for actuating said regulating means, means including a timing device for establishing a periodic operating cycle for said drive, and a control actuated by said differential pressure means for varying the number of operative intervals of said drive in each said cycle in direct relation with the magnitude of change in the consistency of said stock.

4. Apparatus of the character described for maintaining the consistency of the fluid in a container within a predeterminedconsistency range comprising a pump, means connecting the inlet of said pump to said container to eirect continuous withdrawal of a specimen of said' fluid, a flow passage providing a return connection from the outlet of saidpump to said container, said passage having such flow resistance as to provide a readily measurable pressure drop or the: fluid flowing therethrough in relation to the consistency of said fluid, means including a plurality of pressure connection with said passage for continuously measuring said ressure drop, means for regulating the consistency of said fluid in said container, a drive controlled by said measuring means for actuating said regulating means when the consistency of said fiuid exceeds said predetermined range, and a control operative in accordance with a predetermined time cycle for causing intermittent interruption of the operation of said drive to limit the correcting action of said regulating means to increments having a di- "rect relation to the magnitude of change in said consistency.

5. Apparatus for maintaining a predetermined range of consistency for the fluid flowing through a conduit comprising a pump, means connecting the inlet of said pump to said conduit to effect continuous withdrawal of a specimen of said fluid, a flow passage providing a return connection from the outlet of said pump to said conduit and connecting with said conduit at substantially the same pressure level as said inlet connecting means, said passage having such flow resistance as to provide a readily measurable pressure drop of the stock flowing therethrou h in relation to the consistency of aid stock, differential pressure means including a movable part having a plurality of pressure connections with said passage for measuring said pressure drop, a counterbalance for establishing a substantially neutral position for said movable part when the consistency of said fluid is within said predetermined range, means for regulating the consistency of said fluid, a first actuating member for said regulating means movable in response to movement of said movable part. a second actuating member coo erating with said first actuating member to actuate said re ulating means in response to movement of said movable part from said neutral position, and a control for varyin the frequency and the duration of the o erative intervals of said regulating means in substantially direct relation to the magnit de of chan e in the consistency of said fluid and the resulting extent of movement of said first actuating member.

6. Apparatus of the character de cribed for maintainin a predetermined consistency ran e for the aper makin stock in the stock sup ly system of a aper ma h ne. said svstem including a condu t throu h which said stock flows, said appa at s com rising a pum means connect- 'with said passa e for measuring said p essure drop, means for regulating the consistency of said stock, means including a drive actuated movement of said movab e part for operat ng said regulating means, and a control operative in accordance with a predetermined time cycle for causing intermittent interruption of the operation of said operating means to limit the correcting act on of said re ulating means to increments having a direct relation to the magnitude of change in said consistency.

7. Apparatus of the character described for maintaining the consistency of the fluid in a container within a predetermined consistency range comprising a pump, means connecting the inlet of said pump to said'container to effect continuous withdrawal of a specimen of said fluid, a flow passage providing a return connection from the zoutlet of said pump to said container, said passage having such flow resistance as to provide a 20 readily measurable pressure drop of the fluid flowing therethrough in relation to the consistency of said fluid, differential pressure means including a movable part having a plurality of pressure connections with said passage for measuring said pressure drop, a counterbalance for establishing a substantially neutral position for said movable part when the consistency of said fluid is within said predetermined range, a control circuit including a pair of relatively movable control members for effecting regulation of the consistency of said fluid, means mounting one of said circuit control members for movement in direct relation to the movement of said movable part, and a drive for causing continuous oscillating movement of the other of said circuit control members with respect to said movably mounted control member to effect intermittent interruption of said control circuit when said movably mounted circuit control member is within the oscillating range of said oscillating circuit control member.

8. Apparatus of the character described for maintaining the consistency of the fluid in a container within a predetermined consistency range, comprising a pump, means connecting the inlet of said pump to said container to effect continuous withdrawal of a specimen of said fluid, a flow passage providing a return connection from the outlet of said pump to said container, said passage having such flow resistance as to provide a readily measurable pressure drop of the fluid flowing therethrough in relation to the consistency of said fluid, differential pressure means including a movable part having a plurality of pressure connections with said passage for measuring said pressure drop, a counterbalance for establishing a neutral position for said movable part when the consistency of said fluid is within said predetermined range, a control circuit including a pair of relatively movable control members for effecting regulation of the consistency of said fluid, a polygonal cam having a corresponding plurality of corners forming high points, means mounting said cam for rotation about a predetermined axis, the corners of said cam being located at relatively different radial distances from said axis, means forming a flexible su port for one of said circuit control members maintaining said member in contact with said cam to cause said member to oscillate in periodic cycles each comprising a plurality of spaced high points of different heights, corresponding to said corners of said cam, and a support connecting the other of said control members to said movable part for movement therewith relative to said oscillating control member in direct relation to the response of said differential pressure means.

9. Apparatus of the character described for maintaining a predetermined consistency range for the paper making stock in the stock supply system of a paper machine, said system including a conduit through which said stock flows, said apparatus comprising a pump, means connecting the inlet of said pump to said conduit to effect continuous withdrawal of a specimen of said stock, a flow passage providing a return connection from the outlet of said pump to said conduit and connecting with said conduit at substantially the same pressure level as said inlet connecting means, said passage having such flow resistance as to provide a readily measurable pressure drop of the stock flowing therethrough in relation to the consistency of said stock, differential pressure responsive means including a movable part, means providing pressure connections between said differential pressure means and the inlet and outlet of said pump, a counterbalance for establishing a substantially neutral position for said movable part when the consistency of said stock is within said predetermined range, means for regulating the consistency of said stock, an actuating member for said regulating means movable in response to movement of" said movable part, and a control cooperating with said actuating member to actuate said regulating means in response to movement of said movable part from said neutral position.

10. Apparatus for maintaining a predetermined consistency in a fluid, comprising a gear pump including a casing defining an inlet and an outlet, a pair of cooperating impeller gears in said casing, means for connecting said inlet to a. supply of said fluid, means for connecting said outlet to said supply of fluid, each of the teeth of. said gears being so proportioned as to have clearance between adjacent teeth on the other of said gears, means separate from teeth providing a driving connection between said gears maintaining said teeth in angularly spaced relation to prevent pinching of suspended matter in said fluid, means including pressure connections with said inlet and said outlet for measuring the relative pressures in said fluid adjacent said inlet and adjacent said outlet, and means including. avalve controlled by said. measuring means for regulating the consistency of said fluid.

11. Apparatus for maintaining a predetermined consistency in a fluid, comprising a gear pump including a casing defining an inlet and an outlet, a pair of cooperating impeller gears in said casing, means for connecting said. inlet to a supply of said fluid, means for connecting said outlet to said supply of fluid, each of the teeth of said gears being so proportioned as to have clearance between adjacent teeth on the other of said gears, means separate from said teeth providing a driving connection between said gears maintaining said teeth in angularly spaced relation to prevent pinching of suspended matter in said fluid, said gears and said casing being so proportioned as to leave clearance between the teeth of said gears and the adjacent portions of said casing facilitating slippage of said fluid in directions opposite to the direction of. pumping of said pump, means including pressure connections with said inlet and said outlet for measuring the relative pressures in said fluid adjacent said inlet and: adjacent said outlet, means including a valve controlled by said measuring means for regulating the consistency of said fluid.

12. Apparatus for maintaining a predetermined consistency in a fluid, comprising a gear pump including a casing defining an inlet and an outlet, means cooperating with said casing to form a chamber having an open connection tosaid inlet, means cooperating with said casing to form a second chamber having an open connection to said outlet, a flexible and substantially water impervious diaphragm mounted Within each said chamber to divide said chamber into inner and outer sections and to prevent materials suspended in said fluid from entering each said outer chamber section, means for filling each said outer chamber section with a pressure transmitting fluid, differential pressureresponsive means including a movable member having a pressure connection with each said outer chamber section, and means including a valve controlled by said diflerential pressure means for. regulating the consistency of said fluid in accordance: with.

the difierence. between the pressures. existing in said outer chamber sections.

13'. Apparatus for maintaining a predetermined consistency in a fluid, comprising. a gearpump including a casing defining an inlet and an outlet, a pair of cooperating impeller gears in said casing, means for connecting said inlet, tov a supply of. said fluid, means for connecting. said outlet to said supply of fluid, each of, the teeth of said. gears being sov proportioned as to have clearance between adjacent teeth on the other of said gears, means separate from said teeth providing a driving connection between said gears maintaining said teeth inangularly spaced rela-- tion to prevent pinching of suspended matter in said fluid, said gears and said casing being so proportioned as to. leave clearance between the teeth of saidv gears and the. adjacent portions: of said casing. facilitating slippage oi said, fluid in directions opposite to the direction. of. pumping: of said pump, diflerential. pressure responsive means including a movable member, means. providing pressure connections between. said. pressure responsive means and said inlet and between. said pressure responsive means and; said outlet,. and means including a valve controlled by said differential pressure means for regulating the consistency of said fluid in accordance with the diiierential pressure effective on said pressure responsive means.

14. l-ipparatusv of the character described for maintaining a predetermined freeness range for the paper making stock in a stock supply system including conduits and a refiner having means for regulating the refining action thereof to vary the .freeness of the stock discharged therefrom, comprising a flow passage having both. ends thereof connected. With said stock supply system at positions located on the discharge side of said refiner, means for continuously forcing stock from said refiner through said passage, said passage having such flow resistance as to provide a readily measurable pressure drop of the stock flowing therethrough in relation to the freeness of said stock, means including a plurality of pressure connections with said passage for continuously measuring said pressure drop, means for controlling said refiner regulating means to vary the freeness of the stock supplied to said passage, means including an adjustable counterbalance for adjusting said measuring means to maintain said pressure drop within a predetermined pressure range corresponding to said predetermined freehess range, and means operatively connecting said measuring means and said controlling means to. effect actuation of said regulating means when said measured pressure. drop exceeds said predetermined pressure. range.

1.5. Apparatus of the character described for maintaining a predetermined freenes range for the paper making stock in a stock supply system comprising a pump, means connecting the inlet of said pump to said stock supply system to eflect continuous withdrawal of stock from said system, a flow passageprovi'ding a return connection from the outlet of said pump-to said system, said passage having such flow resistance as to provide a readily measurable pressure drop of the stock flowing therethrough in relation to the freeness of said stock, means including pressure connections with said passage for continuously measuring said pressure drop, means in said system ahead of" said pump inlet for varying the freeness of said stock, means including an adjustable counterbalance forad justi'ng said meas- 2;; uring means to maintain said pressure drop within a predetermined pressure range corresponding to said predetermined freeness range, and means electrically connected with said measuring means for efiecting a correcting action of said varying means when said pressure drop exceeds said pressure range.

16. Apparatus of the character described for maintaining a predetermined freeness range for the paper making stock in a stock supply system comprising a pump, mean connecting the inlet of said pump to said stock supply system to effect continuous withdrawal of stock from said system, a flow passage providing a return connection from the outlet of said pump to said system, said passage having such flow resistance as to provide a readily measurable pressure drop of the stock flowing therethrough in relation to the freeness of said stools, differential pressure means including a member movable in response to variation in the pressures effective thereon, means providing pressure connections to said differential pressure means from the inlet and outlet sides of said pump, means including an adjustable counterbalance for balancing said differential pressure means in a neutral position when said pressure drop is within a predetermined pressure range corresponding to said predetermined freeness range, electrically operated means in said system ahead of said inlet for varying the freeness of said stock, and means electrically connecting said differential pressure means and said varying means to effect correctin action of said varying means in response to movement of said differential pressure means from said neutral position.

1'7. Apparatus of the character described for maintaining a predetermined freeness range for the paper making stock in a stock supply system comprising a pump, means connecting the inlet of said pump to said stock supply system to effect continuous withdrawal of stock from said system, a flow passage providing a return connection from the outlet of said pump to said system, said passage having such fiow resistance as to provide a readily measurable pressure drop of the stock flowing therethrough in relation to the freeness of said stock, means including pressure connections with said passage for continuously measuring said pressure drop, intermittently operable means in said system ahead of said pump inlet for varying the freeness of said stock, a drive controlled by said measuring means for actuating said varying means, and a periodically operable control for varying the frequency and duration of the operative intervals of said drive in direct relation to the magnitude of change in the freeness of said stock.

18. Apparatus of the character described for maintaining a predetermined freeness range for the paper making stock in a stock supply system including conduits and a refiner having a relatively rotatable plug and shell, comprising means for regulating the refining action of said refiner by varying the axial relation of said plug and shell to vary the freeness of the stock discharged from said refiner, a pump, means connecting the inlet of said pump to said stock supply system at a position located on the discharge side of said refiner to effect continuous withdrawal of refined stock from said system, a flow passage providing a return connection from the outlet of said pump to said system, said passage having such flow resistance as to provide a readily measurable pressure, drop of the stock flowing therethrough in relation to the freeness of said stock, means including pressure connections with said passage for continuously measuring said pressure drop, means for controlling said refiner regulating means to vary the freenes of the stock supplied to said pump, means including an adjustable counterbalance for adjusting said measuring means to maintain said pressure drop within a predeterimned pressure range corresponding to said predetermined freeness range, and means operatively connecting said measuring mean and said controlling means to effect actuation of said regulating means when said measured pressure drop exceeds said predetermined pressure range.

19. A system for supplying paper making stock at predetermined consistency and freeness to a paper machine comprising a refiner, a conduit for supplying raw stock to said refiner at a higher consistency than said predetermined consistency, adjustable means including a valve for admitting water to said conduit ahead of said refiner to reduce the consistency of said stock, a flow passage connected at both ends with said conduit at positions between said adjustable means and said refiner, means for continuously forcing stock through said fiow passage, said passage having such fiow resistance as to provide a readily measurable pressure drop of the stock fiowing therethrough in relation to the consistency of said stock, means including pressure connections with said passage for continuously measuring said pressure drop, means actuatedby said measuring means for controlling said adjustable means to admit water to said conduit at a sufficient rate to maintain a predetermined said pressure drop corresponding to said predetermined consistency, a second conduit for conveying refined stock from said refiner, a second fiow passage connected at both ends with said second conduit, means for continuously forcing stock from said refiner through said second fiow passage, said second passage having such fiow resistance as to provide a readily measurable pressure drop of the refined stock flowing therethrough related to the freeness of said stock, second measuring means including pressure connections with said second passage for continuously measuring said pressure drop in said second passage, means for adjusting the refining action of said refiner to vary the freeness of the stock refined thereby, and means controlled by said second named measuring means for actuating said adjusting means to maintain a predetermined pressure drop in said second passage corresponding to said predetermined freeness.

20. A system for supplying paper making stock at predetermined consistency and freeness to a paper machine comprising a refiner, a conduit for supplying raw stock to said refiner at a higher consistency than said predetermined consistency, adjustable means including a valve for admitting water to said conduit ahead of said refiner to reduce the consistency of said stock, a pump having its inlet and outlet connected to said conduit at positions located between said adjustable means and said refiner for continuously withdrawing stock and then returning said stock to said conduit, differential pressure means having pressure connections with the inlet and outlet of said pump and including a member movable in response to changes in the relative pressures adjacent the inlet and outlet of said pump, means actuated by said differential pressure means for controlling said adjustable means to admit water to said conduit at a sufiicient rate to maintain a predetermined pressure drop across said pump in relation to said predetermined stock consistency, a second conduit for conveying stock from said refiner, a second pump having its inlet and outlet connected to said second conduit for continuously withdrawing stock from said refiner and then returning said stock to said second conduit, differential pressure means having pressure connections with the inlet and outlet of said pump and including a member movable in response to changes in the relative pressures adjacent the inlet and outlet of said second pump, and means including a drive actuated by said second named difierential pressure means for adjusting the refining action of said refiner to maintain a predetermined pressure drop across said second pump in relation to said predetermined stock freeness.

STEPHEN A. STAEGE.

26 REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 449,251 Decker et a1 Mar. 31, 1891 1,420,348 Swift June 20, 1922 1,641,673 Hall Sept. 6, 1927 1,789,386 Kalle Jan. 20, 1931 1,945,822 Nivling Feb. 6, 1934 2,027,660 Wells Jan. 14, 1936 2,242,419 Cowles May 20, 1941 2,272,970 Frymoyer Feb. 10, 1942 2,392,026 Cram Jan. 1, 1946 2,460,278 Cook Feb. 1, 1949 

